The widow of Zarephath said these words to Elijah after he had raised her son from the dead. However, 1 Kings 17:9 quotes God saying:

"Arise, go to Zarephath, which belongs to Sidon, and dwell there. See, I have commanded a widow there to provide for you."

First Kings 17:14 records Elijah’s promise to the widow, “'The bin of flour shall not be used up, nor shall the jar of oil run dry, until the day the Lord sends rain on the earth.” It happened just as Elijah predicted.

Still it was only after Elijah raised her son from the dead that she said, “Now by this I know that you are a man of God.”

There is a message here for believers today who desire to lead the lost to the Lord, to bring believers back to the Lord or to teach believers the message of grace. It may take more than just one or two contacts with them for them to be convinced that we are from God and that our words are from God.   

Our best preparation for reaching others is living the life of grace. Galatians 3:1 records Paul writing:

O foolish Galatians! Who has bewitched you that you should not obey the truth, before whose eyes Jesus Christ was clearly portrayed among you as crucified?